1. Field of the Invention
The present invention relates to an inclined engine having its cylinder inclined, and more particularly to an inclined engine having such a construction as to have a governor gear of a centrifugal governor adapted to be rotated by a torque of a crankshaft.
2. Description of the Earlier Technology
Conventionally, there has been proposed such an engine that a valve operating cam gear of a valve operating mechanism and a governor gear of a centrifugal governor are driven by rotation of a crankshaft gear fixedly secured to a crankshaft.
The inventor of the present invention knows an engine provided with a governor gear as shown in FIG. 4.
FIG. 4 is a partial vertical sectional view of a vertical engine disclosed in the Japanese Patent Laid Open Publication No. 5-86825.
This engine 90 has a small diameter crankshaft gear 92 and a large diameter crankshaft gear 93 fixedly secured to a crankshaft 91, a valve operating cam gear 94 engaged with the small diameter crankshaft gear 92 and a balancer gear 95 engaged with the large diameter crankshaft gear 93. By engaging the valve operating cam gear 94 with a governor gear 97 arranged at a lower portion of a crank chamber 96, a torque of the small diameter crankshaft gear 92 is transmitted to the governor gear 97 through the valve operating cam gear 94.
On one hand, conventionally there has been proposed such an inclined engine as to have an axial direction of an engine cylinder inclined with respect to a vertical axis and a horizontal axis for decreasing a total height of the engine or due to restrictions on an engine mounting space. For example, when an engine is inclined by inclining an cylinder 98 of the vertical engine 90 shown in FIG. 4 toward a direction 99 indicated by an arrow, it can be found that a space for arranging the governor gear 97 doesn't exist at a location of a right lower portion of the crank chamber 96. In this case, the governor gear 97 may be arranged within the crank chamber 96 by the following two methods.
A first method has such a construction that, as shown in FIG. 5(A), only a small diameter crankshaft gear 100 is fixedly secured to the crankshaft 91, the valve operating cam gear 94 is engaged with the small diameter crankshaft gear 100, and a large diameter governor gear 102 is engaged with the same small diameter crankshaft gear 100 so as not to interfere with a connecting rod, a counter weight 101 and so on.
A second method has such a construction that, as shown in FIG. 5(B), a small diameter crankshaft gear 106 and a large diameter crankshaft gear 104 are fixedly secured to the crankshaft 91, the valve operating cam gear 94 is engaged with the small diameter crankshaft gear 106, and a governor gear 103 is engaged with the large diameter crankshaft gear 104. Also in this construction, it is necessary to considerably increase a diameter of the large diameter crankshaft gear 104 so that a governor mechanism (not illustrated) fixedly secured to the a governor gear 103 doesn't interfere with a connecting rod, a counter weight 101 and so on.
Conventional examples as mentioned above have the following problems.
First, with the first method as shown in FIG. 5(A), since it is necessary to arrange the large diameter governor gear 102 so as not to interfere with the connecting rod, the counter weight 101 and so on, there appears such a problem that a portion of the crank chamber where the large diameter governor gear 102 is arranged projects out. This is because, when the large diameter governor gear 102 having a radius L which does not interfere with the counter weight 101 and so on is employed therein, the radius L also elongates outwardly from a center of a governor shaft 105 and therefore the crank chamber can't help becoming larger for accommodating the large diameter governor gear 102. Further, since the rotational speed transmitted from the crankshaft 91 to the governor shaft 105 is reduced, there appears another problem that sensitivity of the centrifugal governor becomes worse.
Next, with the second method as shown in FIG. 5(B), since the rotational speed of the governor shaft 105 is increased in comparison with that of the crankshaft 91, the sensitivity of the centrifugal governor becomes better, But there is a problem that a depth of the crank chamber in the lengthwise direction of the crankshaft 91 becomes larger because it should be more increased by a thickness d of the large diameter crankshaft gear 104 in comparison with a construction having only the small diameter crankshaft gear 106 arranged.
In short, in the inclined engine, even though either of the first method and the second method is adopted, there is a problem that the crank chamber of the engine becomes large and thus an advantage of employing the inclined engine for compact arrangement is diminished.